Means for tableting sugar



1 Feb. 21, 1956 L. H. BOWES 2,735,380

MEANS FOR TABLETING SUGAR Filed Dec. 11, 1953 INVENTOR ATTORNEY United States Patent 2,735,380 MEANS FOR TABLETING SUGAR Leslie H. Bowes, Akron, Ohio Application December 11, 1953, Serial No. 397,581 1 Claim. (Cl. 107-17) This invention relates to the preparation of substances in tablet form, and it has particular reference to means for tableting sugar, and combinations of sugar with other substances, such as salt, condiments, flavoring materials, coloring materials, and the like which serve to make the tablets suitable for use in the canning industry, as confections and for other purposes, especially when a predetermined amount of sugar, or of sugar and added substances, is required or desired.

As is well known, tablets of various materials have been, and are now, made in tableting machines of the die and punch type in which a plurality of die cavities in a die block are filled with the material to be tableted and the material in each cavity is then subjected to compacting and molding pressure exerted upon it by reciprocatively travelling upper and lower punches so associated and so movable with respect to the die cavity and to each other that after the molding of the tablets has been completed one of such punches, usually the lower punch, will serve to eject the tablet from the cavity, the other punch meanwhile acting in the nature of a follower moving substantially in unison with the movement of the tablet being ejected.

Heretofore great difficulty has been encountered in such tableting of sugar, and of sugar with other materials and substances added, due to the fact that the punches have a tendency to stick to the wall of the die cavity, or the formed tablets stick to such walls, thus tending to arrest movement of the punches, and particularly of the lower, or ejecting punch, with the result either that the tableting machine is jammed or the tablets are broken and unsalable. Hence, it has been found that in the tableting of sugar, and of the majority of materials containing sugar, it is necessary to supply a lubricant for the die cavity and punches, usually as an additive to the material to be tableted. In providing a lubricant for use with such sugar containing materials it is customary to use some derivative or salt of stearic acid, such as magnesium stearate or calcium stearate, either alone or combined with another substance such as purified talcum or dried corn starch.

Obviously, lubricants of these types are adulterants of the materials to be tableted and, though usually harmless when the tablets are used for human consumption, are nevertheless impurities, especially where pure sugar tablets are called for.

The object of the present invention is to provide means for tableting sugar, and mixtures of sugar with other desired materials, in which the addition to the sugar, or to the sugar and such materials, of a lubricant is obviated, thus making possible the tableting of unadulterated sugar or sugar mixtures and hence providing for the furnishing of tablets of pure sugar or sugar mixtures for uses in which the presence of an adulterant, such as any of the lubricants now commonly used, would be prohibited.

To this end the invention comprises means for preventing the sticking or jamming of the punches in the die cavity of a tableting machine, and likewise the sticking or jamming of the molded or compressed tablets and the impossibility of their proper ejection, especially in relation to the tableting of sugar and mixtures containing sugar, in which the die cavity is subjected to the presence of water vapor, preferably live steam, most effectively directed against the cavity wall by its introduction thereinto around a portion of one of the punches, preferably the lower tablet ejecting punch, which portion is of less diameter than the die cavity and the operative heads of the punches which have a very close sliding fit therewith, to thus provide an annular vapor-receiving space, all as will be explained hereinafter more fully and finally claimed.

In the accompanying drawing illustrating the invention, in the several figures of which like parts are similarly designated.

Figs. 1, 2 and 3 are similar fragmentary sectional elevations of schematic form showing, respectivety, the die cavity of a tableting machine with the punches thereof in the filling, molding or compressing, and ejecting positions.

As is customary in tableting machines of the die cavity and punch type, the parts illustrated include a die block 1 provided with a die cavity 2 with which cooperate an upper punch 3 and a lower or ejecting punch 4, and the operative heads 5 and 6, respectively, of these punches are formed to produce tablets of desired shapes or surface characteristics and are of such diameter as to have a very close sliding fit with the wall of the die cavity 2.

In accordance with the invention the lower or ejecting punch 4 is formed below its closely fitting head 6 with a shank 7 of a reduced diameter sufiiciently less than the diameter of the die cavity 2 to provide between its surface and the wall of the die cavity (Figs. 2 and 3) an annular space 8 into which water vapor, preferably live steam, may enter. As shown, the vapor (steam) may be confined within a jacket 9 enclosing a desired axial extent of the shank 7 of the lower punch 4 and may be introduced into the chamber 10 formed by this jacket through a pipe 11. A drain pipe 12 is preferably provided to evacuate water of condensation from the chamber 10.

It will be noted that at all times the shank 7 of the lower punch 4 is subjected to contact with the vapor (steam) with which it is surrounded, and this is true whether this punch is lowered (Fig. 1) into the die-filling position, is raised (Fig. 2) into the tablet molding or compressing position, or is further raised (Fig. 3) into the tablet ejecting position. Also, the tablet molding or compressing position of the two punches 3 and 4 (Fig. 2) being substantially midway axially of the die cavity 2, and the ejecting position of the lower or ejecting punch 4 (Fig. 3) being such as to locate its operative head 6 at the uper extremity of the die cavity 2 and well above the zone of the die cavity in which the tablet is molded or compressed, this zone of the cavity wall will, when a tablet is being ejected, be subjected to contact of the vapor (steam) within the annular space 8. Hence, practically the entire axial extent of the wall of the die cavity can and will be subjected to contact of the vapor admitted into the annular space 8.

In practice, perfect tablets of pure sugar have been produced by a tableting machine operated in accordance with applicants invention without any sticking or jamming either of the tablets during the ejecting thereof or of either of the punches, and applicant is of the opinion that this is possible due to the deposition from the water vapor upon the wall of the die cavity of an infinitesimal film or skin of moisture which serves as an eifective lubricant.

Also, it has been found that, in practicing the invention, most satisfactory results are obtained where the die and punch parts are made of manganese bronze or a bronze commercially known as Ampco Bronze #18, or Ampco Bronze #20.

Various changes and modifications are considered to be Within the principle of the invention and the scope of the following claim.

What I claim is:

Apparatus for forming compressed tablets, including means providing a die cavity, an ejecting punch reciprocable axially of said cavity having an operative head in intimate sliding contact with the wall of said cavity and a shank of less diameter than the diameter of said cavity, and means for introducing steam into said cavity around the shank of said punch as the punch reciprocates.

References Cited in the file of this patent UNITED STATES PATENTS 551,062 Tilden Dec. 10, 1895 1,327,806 Bunde Jan. 13, 1920 2,262,155 Andrews Nov. 11, 1941 2,444,282 Creevy June 29, 1948 

